[MC-280231] All forceloaded chunks are removed when game tests finish

How to reproduce

Mark a chunk to be force-loaded
```
/forceload add 50 0 50 0
```
✔ Validate that this chunk is now force-loaded
```
/forceload query
```
Run any test instance
```
/test run minecraft:always_pass
```
❌ Notice that the chunk is no longer force-loaded
```
/forceload query
```

Expected behavior

Chunks that were previously marked as force-loaded by commands would stay being force-loaded.

Comments 2

MrMuskle 2025-02-20T18:15:30Z

I am able to reproduce the reported behavior. It has been present ever since 25w03a, when the game test system was made available.

slicedlime 2025-02-21T08:35:09Z

The test system is not meant to interact with any other systems in existing worlds. Running tests will assume ownership of your world, and like stated in the changelog: “The test framework expects to run tests in a separate superflat world”. Trying to mix it with other systems will have undefined results.